1. Field of the Invention
The present invention relates to a method and apparatus for disrupting cells or viruses using gold nanorods and amplifying nucleic acids released from the disrupted cells or viruses.
2. Description of the Related Art
Gold nanorods are gold nanoparticles in a rod form possessing good light absorption properties in the range of visible light to near infrared light. As illustrated in FIG. 1, it is known that the wavelength of light absorbed by gold nanorods varies according to a ratio of the cross-sectional diameter (hereinafter referred to as “diameter”) to the length of the gold nanorods (Mohamed, M. B. et al. (2000) Chemical Physics Letters, 317: 517-523). For example, FIG. 1 illustrates the absorption spectra of gold nanorods having length to diameter ratios of 2.0, 2.6, 3.3, 4.3, and 5.4, (FIG. 1, (I), (II), (III), (IV), and (V) respectively).
Cell lysis is conventionally performed using a variety of methods including mechanical, chemical, thermal, electrical, ultrasonic or microwave methods (Taylor, M. T. et al. (2001) Anal. Chem., 73: 492-496). Additionally, a laser provides many advantages for use in the disruption of cells and can be readily applied to Lab-on-a-Chip (LOC) methods (Li, H. et al. (2001) Anal. Chem, 73: 4625-4631).
U.S. Patent Publication No. 2003/96429 A1 discloses a laser-induced cell lysis system. When only a laser is used, efficient cell lysis does not occur. For example, an experiment using E. coli placed in a very clear solution confirmed that when irradiating with only a laser, a low cell lysis efficiency was obtained. Further, the concentration of DNA measured after irradiating the cell sample with a laser for 150 seconds was 3.77 ng/μl, whereas the concentration of DNA measured after boiling cells in a comparable cell sample at 95° C. for 5 minutes was 6.15 ng/μl. The lower level of DNA obtained as the result of cell lysis by laser irradiation resulted because the laser energy was not effectively transferred to the cells.
U.S. Pat. No. 6,685,730 discloses optically-absorbing nanoparticles for enhanced tissue repair. This patent relates to a method of joining tissue comprising: delivering nanoparticles having dimensions of 1 to 1000 nanometers that absorb light at one or more wavelengths to the tissue to be joined; and exposing the nanoparticles to light at one or more wavelengths that are absorbed by the nanoparticles. This method of using a laser and nanoparticles causes only a loss of function in the cells. There is no description of a method for disrupting cells using a solution containing cells and gold nanorods.
A conventional Laser-irradiated Magnetic Beads System (LIMBS) disrupts cells using micro-magnetic beads to obtain genetic materials. However, in this case, it is preferred that the magnetic beads be removed from the cellular material prior to subsequent downstream processes. To implement LIMBS in a Lab-on-a-Chip (LOC) method, a membrane for removing the beads should be used or alternatively, a surface structure should be manufactured other than beads, which results in additional costs and low efficiency. In addition, the magnetic beads can adsorb fluorescent materials that are used for real time polymerase chain reaction (PCR), such as SYBR Green dye, and thus, the use of these dyes has been limited.
Thus, the inventors conducted extensive research in order to address the above problems and discovered that micro-magnetic beads can be replaced with gold nanorods to remarkably increase the surface area, thereby improving the efficiency of disrupting cells or viruses, and attaining high levels of cell disruption, even when only small amounts of nanorods are used. In particular, gold nanorods were found to not significantly affect the optical properties of a solution. Although these nanomaterials are not removed after using them, genetic materials can be detected using subsequent real time PCR methods. PCR can be continuously performed without removing the gold nanorods following the disruption of cells or viruses.